3x^2=3.6x+3.9

Solution for 3x^2=3.6x+3.9 equation:

3x^2=3.6x+3.9

We move all terms to the left:

3x^2-(3.6x+3.9)=0

We get rid of parentheses

3x^2-3.6x-3.9=0

a = 3; b = -3.6; c = -3.9;
Δ = b2-4ac
Δ = -3.62-4·3·(-3.9)
Δ = 59.76
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-3.6)-\sqrt{59.76}}{2*3}=\frac{3.6-\sqrt{59.76}}{6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-3.6)+\sqrt{59.76}}{2*3}=\frac{3.6+\sqrt{59.76}}{6}
$